A spark is an incandescent particle. Sparks may be produced by pyrotechnics, by metalworking or as a by-product of fires, especially when burning wood.
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👉 Spark (fire) in the context of Particle
In the physical sciences, a particle (or corpuscle in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass. They vary greatly in size or quantity, from subatomic particles like the electron, to microscopic particles like atoms and molecules, to macroscopic particles like powders and other granular materials. Particles can also be used to create scientific models of even larger objects depending on their density, such as humans moving in a crowd or celestial bodies in motion.
The term particle is rather general in meaning, and is refined as needed by various scientific fields. Anything that is composed of particles may be referred to as being particulate. However, the noun particulate is most frequently used to refer to pollutants in the Earth's atmosphere, which are a suspension of unconnected particles, rather than a connected particle aggregation.
In this Dossier
Spark (fire) in the context of Grinding (abrasive cutting)
Grinding is a type of abrasive machining process which uses a grinding wheel as cutting tool.
A wide variety of machines are used for grinding, best classified as portable or stationary:
Spark (fire) in the context of Touch hole
A touch hole, also known as a cannon vent, is a small hole at the rear (breech) portion of the barrel of a muzzleloading gun or cannon. The hole provides external access of an ignition spark into the breech chamber of the barrel (where the combustion of the propellant occurs), either with a slow match (matchlock), a linstock or a flash pan ignited by some type of pyrite- (wheellock) or flint-based gunlock (snaplock, snaphaunce, and flintlock), which will initiate the combustion of the main gunpowder charge. Without a touch hole, it would be nearly impossible to ignite the powder because the only otherwise access into the barrel is from the front via the muzzle, which is obturated by the projectile.
In the later caplock firearms, the ignition sparks are generated by a shock-sensitive percussion cap placed over a conical "nipple", which has a hollow conduit known as the flash channel, that leads into the barrel and serves the same function as the touch hole.
Spark (fire) in the context of Autoignition temperature
The autoignition temperature (often called self-ignition temperature, spontaneous ignition temperature, minimum ignition temperature, or shortly ignition temperature, formerly also known as kindling point) of a substance is the lowest temperature at which it spontaneously ignites in a normal atmosphere without an external source of ignition, such as a flame or spark. This temperature is required to supply the activation energy needed for combustion. The temperature at which a chemical ignites decreases as the pressure is decreased.
Substances which spontaneously ignite in a normal atmosphere at naturally ambient temperatures are termed pyrophoric.
Spark (fire) in the context of Ember
An ember, also called a hot coal, is a hot lump of smouldering solid fuel, typically glowing, composed of greatly heated wood, coal, or other carbon-based material. Embers (hot coals) can exist within, remain after, or sometimes precede, a fire. Embers are, in some cases, as hot as the fire which created them. They radiate a substantial amount of heat long after the fire has been extinguished, and if not taken care of properly can rekindle a fire that is thought to be completely extinguished and can pose a fire hazard. In order to avoid the danger of accidentally spreading a fire, many campers pour water on the embers or cover them in dirt. Alternatively, embers can be used to relight a fire after it has gone out without the need to rebuild the fire – in a conventional fireplace, a fire can easily be relit up to 12 hours after it goes out, provided that there is enough space for air to circulate between the embers and the introduced fuel.
They are often used for cooking, such as in charcoal barbecues. This is because embers radiate a more consistent form of heat, as opposed to an open fire, which is constantly changing along with the heat it radiates.